This may not be the right place for this but I figure it's at least a good starting place:

The default recipe in Calibre is working quite well for me in getting all my articles; I end up with a much nicer ePub than Instapaper offers and it's great having the images in articles included. I was wondering if there's any way to have the images centered on the page instead of left-aligned; using the css it'd be a matter of simply setting the margin property on any img element to "0 auto 0 auto". Possible at all?